Subject: HRI/MRI IP TV4 Flash report Date: Fri, 28 Feb 2003 22:03:52 -0500 From: Dennis Wellnitz Hi all, Today (Friday, February 28) has been a more relaxed day than previous days, as we are taking CCD darks for both the HRI and the MRI while cooling the Instruments to operating temperatures. Because the Instruments and CCDs cool slowly, the dark measurements are spaced relatively widely in time, providing us time to have some meetings and analyze recently acquired data. At 8:25 pm last night we attempted to flood the Rambo shroud with liquid nitrogen, but discovered a leak in one of the copper tubes outside the chamber. After the copper tube was replaced, the shroud was flooded at about 9 pm. At that time the instruments were both at about -30 C, having been maintained at that temperature for most of the day for MRI tests at ITS operating temperature. By 10 am the MRI and HRI structure temperatures had dropped to about -100 C. Because we were taking data during the day, the temperatures dropped more slowly. When we finished taking data at 5 pm we turned off all the heaters (except those that maintain the temperatures of the electronics within their survival zones) to permit the temperatures to continue to drop rapidly overnight tonight. By 7 pm tonight the MRI structure temperature had dropped to -111 C, and the HRI SIM temperature had dropped to -117 C. We are also letting the CCD temperatures drop overnight to the temperature at which the survival heaters will turn on: -109 C; at 7 pm they were at -91 for the MRI and -93 for the HRI. The IR-FPA was down to -145 C at 7 pm. We will continue working Saturday, starting at about 9 am. The plan is to begin looking at the MRI flat fields. Please let me know if you have any questions or comments. Also please let me know if you would prefer not to be included on this Flash report distribution list, or if there is someone else who should be included on this distribution list. Dennis